4,806 research outputs found
A note on some constants related to the zeta-function and their relationship with the Gregory coefficients
In this paper new series for the first and second Stieltjes constants (also
known as generalized Euler's constant), as well as for some closely related
constants are obtained. These series contain rational terms only and involve
the so-called Gregory coefficients, which are also known as (reciprocal)
logarithmic numbers, Cauchy numbers of the first kind and Bernoulli numbers of
the second kind. In addition, two interesting series with rational terms are
given for Euler's constant and the constant ln(2*pi), and yet another
generalization of Euler's constant is proposed and various formulas for the
calculation of these constants are obtained. Finally, in the paper, we mention
that almost all the constants considered in this work admit simple
representations via the Ramanujan summation
Vocational education and economic environments : conflict or convergence?
A better understanding of the relationship between economic policies and human capital formation through vocational education and training (VET) will help both development strategists and education planners. With this in mind, the paper begins with a social systems model to trace the impact of the economic environment and policies on the internal and external efficiency of VET. It continues with a discussion of how specific economic policies can shape efforts to improve the internal and external efficiency of VET. Some evidence of this relationship is provided in a review of the VET experience in selected countries. The paper concludes with some tentative lessons for VET lending and sector work as drawn from this review and offers an agenda for the further study and validation of the economic environment thesis.Economic Theory&Research,Vocational&Technical Education,Teaching and Learning,Environmental Economics&Policies,Banks&Banking Reform
How to centralize and normalize quandle extensions
We show that quandle coverings in the sense of Eisermann form a (regular
epi)-reflective subcategory of the category of surjective quandle
homomorphisms, both by using arguments coming from categorical Galois theory
and by constructing concretely a centralization congruence. Moreover, we show
that a similar result holds for normal quandle extensions.Comment: 17 page
The isometries of the cut, metric and hypermetric cones
We show that the symmetry groups of the cut cone Cut(n) and the metric cone
Met(n) both consist of the isometries induced by the permutations on {1,...,n};
that is, Is(Cut(n))=Is(Met(n))=Sym(n) for n>4. For n=4 we have
Is(Cut(4))=Is(Met(4))=Sym(3)xSym(4).
This is then extended to cones containing the cuts as extreme rays and for
which the triangle inequalities are facet-inducing. For instance,
Is(Hyp(n))=Sym(n) for n>4, where Hyp(n) denotes the hypermetric cone.Comment: 8 pages, LaTeX, 2 postscript figure
Thread-Modular Static Analysis for Relaxed Memory Models
We propose a memory-model-aware static program analysis method for accurately
analyzing the behavior of concurrent software running on processors with weak
consistency models such as x86-TSO, SPARC-PSO, and SPARC-RMO. At the center of
our method is a unified framework for deciding the feasibility of inter-thread
interferences to avoid propagating spurious data flows during static analysis
and thus boost the performance of the static analyzer. We formulate the
checking of interference feasibility as a set of Datalog rules which are both
efficiently solvable and general enough to capture a range of hardware-level
memory models. Compared to existing techniques, our method can significantly
reduce the number of bogus alarms as well as unsound proofs. We implemented the
method and evaluated it on a large set of multithreaded C programs. Our
experiments showthe method significantly outperforms state-of-the-art
techniques in terms of accuracy with only moderate run-time overhead.Comment: revised version of the ESEC/FSE 2017 pape
Theoretical prediction and spectroscopic fingerprints of an orbital transition in CeCu2Si2
We show that the heavy-fermion compound CeCu2Si2 undergoes a transition
between two regimes dominated by different crystal-field states. At low
pressure P and low temperature T the Ce 4f electron resides in the atomic
crystal-field ground state, while at high P or T the electron occupancy and
spectral weight is transferred to an excited crystal-field level that
hybridizes more strongly with itinerant states. These findings result from
first-principles dynamical-mean-field-theory calculations. We predict
experimental signatures of this orbital transition in X-ray spectroscopy. The
corresponding fluctuations may be responsible for the second high-pressure
superconducting dome observed in this and similar materials.Comment: 5 pages, 4 figures + 5 supplementary page
Flows on quaternionic-Kaehler and very special real manifolds
BPS solutions of 5-dimensional supergravity correspond to certain gradient
flows on the product M x N of a quaternionic-Kaehler manifold M of negative
scalar curvature and a very special real manifold N of dimension n >=0. Such
gradient flows are generated by the `energy function' f = P^2, where P is a
(bundle-valued) moment map associated to n+1 Killing vector fields on M. We
calculate the Hessian of f at critical points and derive some properties of its
spectrum for general quaternionic-Kaehler manifolds. For the homogeneous
quaternionic-Kaehler manifolds we prove more specific results depending on the
structure of the isotropy group. For example, we show that there always exists
a Killing vector field vanishing at a point p in M such that the Hessian of f
at p has split signature. This generalizes results obtained recently for the
complex hyperbolic plane (universal hypermultiplet) in the context of
5-dimensional supergravity. For symmetric quaternionic-Kaehler manifolds we
show the existence of non-degenerate local extrema of f, for appropriate
Killing vector fields. On the other hand, for the non-symmetric homogeneous
quaternionic-Kaehler manifolds we find degenerate local minima.Comment: 22 page
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